1. Field of the Invention
The present invention relates to a car navigation system, a traffic information providing apparatus, a car navigation device, and a traffic information providing method and program where predicted traffic information is applied, considering meteorological information.
2. Description of the Related Art
A car navigation device of recent years not only displays a shortest distance route to a destination and performs a route guidance according to the shortest distance, but also receives newest traffic information such as a traffic jam and a travel time provided by FM character multiplex broadcasting, for example, from VICS Center (Vehicle Information and Communication System Center), derives a shortest time route with considering the traffic information, and performs a route guidance according to the shortest time route.
However, because newest traffic information used at this time is present traffic information or traffic information a little earlier than present, a guidance route calculated by the car navigation device is not always a shortest time route. For example, in a case that a link A is not jammed at present where a vehicle is scheduled to pass after one hour, even if the link A is predicted to be jammed after the one hour, a guidance route passing such the link A is calculated if based on a calculation method of a current guidance route.
Consequently, for example, in Japanese Patent Laid-Open Publication No. 2003-151079 (paragraphs 0019 to 0052, FIGS. 1 to 4, and 6 to 9) is disclosed a method of predicting time when a vehicle passes and calculating a guidance route, based on traffic information such as a jam at the predicted time and a travel time. According to the method, in a case that the link A scheduled to be passed after one hour is predicted to be jammed after the one hour, it is enabled to calculate such a guidance route that avoids the link A. Meanwhile, the prediction of the traffic information is assumed to consider such a season, a day of the week, and a meteorological phenomenon.
In accordance with the calculation method of the guidance route disclosed in the Japanese Patent Laid-Open Publication No. 2003-151079, although a meteorological condition is assumed to be considered in predicting traffic information, the meteorological condition indicates weather at that time, a static meteorological condition such as a fine weather, rain, and snow. However, a meteorological phenomenon, weather ever changes similarly to a traffic condition of a road, and drastically changes at some time. Then being accompanied with the weather change, the traffic condition also largely changes. Accordingly, if traffic information is predicted with a static meteorological condition at that time, especially in a case that weather suddenly changes, a reliability of the predicted traffic information results in being lowered.
In view of the problems of the conventional technology thus described are strongly requested a car navigation system, a traffic information providing apparatus, a car navigation device, and a traffic information providing method and program configured to predict traffic information, considering meteorological information, and to calculate a guidance route, based on the predicted traffic information.